1. Field of the Invention
The present invention relates to an exercise apparatus, and more particularly to an aquatic exercise apparatus which helps healthy persons remain physically fit and can aid in the rehabilitation of disabled persons.
2. General Background of the Invention
It has long been recognized that exercising is important to promote and maintain good health, and can aid in the rehabilitation of disabled persons. The most common types of exercise comprise physical activity on dry land; however, it is well known that exercising in water can, in many respects, be more advantageous. For some persons, aquatic exercise may be the only practical option available. Such persons include those who, due to automobile accidents or bouts with polio, for example, have restricted or non-existent control over their lower limbs. Other such persons include those who, while they may have excellent leg strength and control, have limited control over their trunk, and are unable to sit or stand upright without support. Water provides buoyant support for their bodies, enabling them to exercise their arms and, depending upon the severity of their condition, their legs by swimming. The majority of these individuals have a difficult time entering the water through means which most of us take for granted (for example, walking into a swimming pool on steps). Accordingly, various devices have been proposed to facilitate their entry into and exit from bodies of water.
U.S. Pat. No. 4,183,106, for example, discloses a device which comprises a chair on which a disabled person sits. The chair swivels between a position above a deck near a swimming pool and a position above the pool. Means are provided to lower the chair into the pool, thereby allowing the person easy access to the pool.
U.S. Pat. No. 4,221,008 discloses a hydraulic chair lift, similar to that described above, which uses domestic water pressure for operation.
U.S. Pat. No. 4,283,803 describes a hydraulically-operated wheelchair submersion device which utilizes water as the hydraulic fluid. A wheelchair is wheeled onto a platform, which lowers into a swimming pool, allowing a disabled individual to easily enter the pool.
Conventional aquatic exercise, such as swimming, is not the only useful type of aquatic exercise. In recent years, athletic trainers and physical therapists have found that many forms of exercise, which have traditionally been performed only on dry land, can be even more beneficial when carried out in water. In fact, due to various injuries sustained or disorders suffered, some individuals, temporarily or permanently, can safely perform certain traditionally land-based exercise, such as running or walking, only in water. This is because the buoyancy of the water helps to reduce the stress on an individual as he exercises. The force at heal strike on a runner's foot on level ground is three times his body weight; each of his feet strike the ground approximately one thousand times per mile. A 150 pound runner therefore applies about 120 tons of pressure to each foot each mile. This is a tremendous amount of stress on the body, and helps explain why most athletes suffer from running injuries at one time or another. For runners susceptible to stress fractures, the ability to exercise without subjecting his body to such punishing stress is a desirable alternative which aquatic exercise can provide. Even excessive walking on land can be disadvantageous for some people, since each leg spends about 60% of the time in the stressful stance phase in which the foot contacts the ground. Other individuals who can benefit from aquatic exercise include obese persons who find it too difficult to ambulate much on land due to the burden of their weight, persons suffering from neuromuscular disorders whose leg muscles can move but are not yet trained to support the person's weight, post-operative patients who need to slowly build up strength in their legs and individuals with limited control over their upper bodies.
Various devices and systems have been proposed which could assist some of these individuals in exercising. U.S. Pat. No. 4,551,108, for example, discloses a system for exercising in water which comprises a buoyant vest and a plurality of lines. The exerciser wears the buoyant vest in a tank of water, and the lines interconnect the vest and the sides of the tank. The vest provides some buoyant support, the lines help to keep the exerciser's head above water and keep his feet above the bottom of the tank. The exerciser can thus run in place in the water, without subjecting his legs to stress or relying on his legs to support his weight. While this system can be helpful for some people, others, particularly those confined to wheelchairs, may have difficulty entering the tank and adjusting the lines to the proper length.
Another system which has been proposed is an animal exercising device disclosed in U.S. Pat. No. 4,332,217. The device comprises a portable water tank with a treadmill in the bottom thereof. In operation, an animal enters the tank and the tank is filled with water. The buoyancy of the animal's body reduces the stress on his legs while he exercises on the treadmill. The exercise sessions are repeated, each time with less water in the tank as the animal's legs are able to bear more weight. Eventually, no water is necessary in the tank. While this device can be useful to aid some people in performing aquatic exercise, it is large and relatively expensive, uses a large quantity of water, and some individuals would find it difficult to enter the tank. Furthermore, varying the level of water in the tank is a time-consuming process.